Phase-change materials from wax-based colloidal dispersions and their process of making

ABSTRACT

This invention generally relates to phase-change materials (PCM) comprising colloidally-protected wax-based microstructures and optionally, an absorbent material such as activated carbon. This invention also relates to such PCMs configured in various physical forms. This invention further relates to a process of configuring such PCMs for a variety of end-use applications in which dampening of temperature fluctuations by absorption and desorption of heat is desired. This invention also relates to PCM with reduced leaking of paraffin from the CPWB microstructures. This invention further relates to preparing colloidally-protected wax-based microstructures in particulate form that function as PCMs.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent ApplicationNo. 62/090,505, filed Dec. 11, 2014, which is hereby incorporated byreference in its entirety.

FIELD

This invention generally relates to phase-change materials (PCM)comprising colloidally-protected wax-based microstructures andoptionally, an absorbent material such as activated carbon. Thisinvention also relates to such PCMs configured in various physicalforms. This invention further relates to a process of configuring suchPCMs for a variety of end-use applications in which dampening oftemperature fluctuations by absorption and desorption of heat isdesired. This invention also relates to PCM with reduced leaking ofparaffin from the CPWB microstructures. This invention further relatesto preparing colloidally-protected wax-based microstructures inparticulate form that function as PCMs.

BACKGROUND

A phase-change material (PCM) is a substance with a high heat of fusion,which, by melting and solidifying at a certain temperature, is capableof storing and releasing large amounts of energy. Heat is absorbed orreleased when the material changes from solid to liquid and vice versa;thus, PCMs are classified as latent-heat storage (LHS) units. The phasechange herein would be the solid-liquid phase change. Depending on themolecular weight and the type of wax material used, one could tailor thephase change for various temperatures. U.S. Pat. No. 6,939,610 describesphase change materials. This patent is incorporated by reference as iffully set forth herein. PCMs take advantage of the latent heat that canbe stored or released from a material over a narrow temperature range.PCMs possess the ability to change their state within a certaintemperature range. These materials absorb energy during the heatingprocess as phase change takes place and release energy to theenvironment in the phase change range during the reverse, that is, thecooling process. Insulation effect reached by the PCM depends ontemperature, time, and the type of material employed as phase changematerial.

Latent-heat storage is one of the most efficient ways of storing thermalenergy. Unlike the sensible heat storage method, the latent-heat storagemethod provides much higher storage density, with a smaller temperaturedifference between storing and releasing heat. Every material absorbsheat when its temperature is rising constantly. The heat stored in thematerial is released into the environment through a reverse coolingprocess. During the cooling process, the material temperature decreasescontinuously. Comparing the heat absorption during the melting processof a phase change material with those in normal materials, much higheramount of heat is absorbed when a PCM melts. A paraffin-PCM, forexample, absorbs approximately 200 kJ/kg of heat when it undergoes amelting process. High amount of heat absorbed by the paraffin in themelting process is released into the surrounding area in a coolingprocess, which starts at the PCM's crystallization temperature.

During the complete melting process, the temperature of the PCM as wellas its surrounding area remains substantially constant. The same is truefor the crystallization process; during the entire crystallizationprocess the temperature of the PCM does not change significantly either.The large heat transfer during the melting process as well as thecrystallization process without significant temperature change makes PCMinteresting as a source of heat storage material in practicalapplications. When temperature increases, the PCM microcapsules absorbheat and store this energy in the liquefied phase-change materials. Whenthe temperature falls, the PCM microcapsules release this stored heatenergy and consequently PCMs solidify.

PCMs can be classified as: (1) organic phase change materials; (2)inorganic phase change materials; and (3) eutectic phase changematerials.

Organic PCMs are most often composed of organic materials such asparaffins, fatty acids, and sugar alcohols. For building applications,paraffinic PCMs are the most commonly used for several reasons. First,paraffinic PCMs are straight chain n-alkane hydrocarbon compounds suchas n-heptadecane and n-eicosane. Their melting temperature and phasechange enthalpy increase with the length of the carbon chain. When thenumber of carbon atoms in the paraffin molecule is between 13 and 28,the melting temperature falls within a range of approximately 23° to140° F. (−5° to 60° C.), a temperature range that covers buildingapplications in most climates around the world. In addition, paraffinicPCMs are chemically inert, nontoxic, reliable, and biocompatible. Theyalso show a negligible sub-cooling effect. Fatty acids are representedby the chemical formula CH₃(CH₂)_(2n)COOH (e.g., capric acid, lauricacid, and palmitic acid). Fatty acids have storage densities verysimilar to paraffins, and like paraffins their melting temperaturesincrease with the length of the molecule. Although chemically stableupon cycling, they tend to react with the environment because they areacidic in nature. Sugar alcohols are a hydrogenated form of acarbohydrate such as D-sorbitol or xylitol, among others. They generallyhave higher latent heat and density than paraffins and fatty acids.Because they melt at temperatures between 194° and 392° F. (90° and 200°C.), though, they are unsuitable for building applications.

These paraffin-based PCMs are made by physical microencapsulation of theparaffin core in a polymeric shell—the microcapsules act as tinycontainers of solids. Generally, microcapsules have walls less than 2 μmin thickness and 20-40 μm in diameter. The microcapsules are produced bydepositing a thin polymer coating on core particles. The corecontents—the active substance—may be released by friction, by pressure,by diffusion through the polymer wall, by dissolution of the polymerwall coating, or by biodegradation. For example, in their application intextiles, the paraffins are either in solid or liquid state. In order toprevent the paraffin's dissolution while in the liquid state, it isenclosed into small plastic spheres with diameters of only a fewmicrometers. These microscopic spheres containing PCM are calledPCM-microcapsules.

Microcapsule production may be achieved by means of physical or chemicaltechniques. The use of some techniques has been limited to the high costof processing, regulatory affairs, and the use of organic solvents,which are concern for health and the environment. Physical methods aremainly spray drying or centrifugal and fluidized bed processes which areinherently not capable of producing microcapsules smaller than 100 □m.Interfacial polymerization techniques are used generally to prepare themicrocapsules.

It is clear that PCM microcapsule materials require a physicaldeposition of a polymeric shell that encases the active material—forexample, paraffing—as core. This physical encasement of the core is anexpensive process as it requires a chemical in situ polymerizationprocess or another deposition technique, for example, chemical vapordeposition. Moreover, the complete and comprehensive encapsulation ofthe core by the polymeric shell can interfere with the efficiency of thecore material, which really provides the PCM character to themicrocapsules.

The present invention addresses the above problems and provides PCMsthat are not a classic core-shell structure but wax-basedmicrostructures that are colloidally protected in a casing by polymericmoieties such as PVOH that provides the same functionality by usingparaffins with various melt point as core. However, the so-called“encapsulation” in the present invention is not a physical deposition ofthe polymeric shell on a core, which is what the art teaches.

SUMMARY OF INVENTION

This invention relates to a phase change material (PCM) comprisingcolloidally-protected wax-based (CPWB) microstructures and optionally anabsorbent material.

This invention relates further relates to a phase change material (PCM)comprising:

(I) said CPWB microstructures, wherein said CPWB microstructurecomprises:

(A) a wax core, and

(B) a polymeric shell;

-   -   wherein said wax core comprises a paraffin component and a        non-paraffin component;        -   wherein said paraffin component comprises at least one            linear alkane wax defined by the general formula CnH2n+2,            where n ranges from 13-80;        -   wherein said non-paraffin component comprises at least one            wax selected from the group consisting of animal-based wax,            plant-based wax, mineral wax, synthetic wax, a wax            containing organic acids and/or esters, anhydrides, an            emulsifier containing a mixture of organic acids and/or            esters, and combinations thereof; and    -   wherein said polymeric shell comprises at least one polymer        selected from the group consisting of polyvinyl alcohol and        copolymers, cellulose ethers, polyethylene oxide,        polyethyleneimines, polyvinylpyrrolidone, and copolymers,        polyethylene glycol, polyacrylamides and poly        (N-isopropylamides), pullulan, sodium alginate, gelatin,        starches, and combinations thereof, and        (II) an absorbent material, wherein said absorbent material        comprises at least one of activated carbon, graphite, bentonite,        deposited carbon, silica gel, activated alumina, zeolites,        molecular sieves, alkali metal alumino-silicate, silica-magnesia        gel, silica-alumina gel, activated alumina, calcium oxide,        calcium carbonate, clay, diatomaceous earth, cyclodextrin, or a        combination thereof.

This invention further relates to such PCM, wherein said PCM'stemperature operating range is defined by the melting point of saidparaffin component comprising at least one linear alkane wax defined bythe general formula CnH2n+2, where n ranges from 13-80, and wherein saidtemperature operating range is characterized the corresponding pressureof the system in which said PCM is used.

This invention also relates to the PCM described above, wherein saidPCM's temperature operating range is from −6° C. to 140°.

This invention also relates to a process for preparing the PCM describedabove, comprising contacting CPWB microstructures with an absorbentmaterial to from said PCM.

This invention also relates to a matrix structure comprising PCM asdescribed above. In one embodiment, this invention further relates tosuch matrix structures, wherein said PCM is in an aqueous emulsion formor a powder form. In another embodiment, this invention relates to asuch matrix structures, wherein the dry-solids weight percent of saidPCM in said aqueous emulsion form, by weight of said matrix structure isin the range of from 10% to 50%; and wherein the solids weight contentof the PCM in said dry powder form is in the range of from 1% to 50% byweight of said matrix structure. In one embodiment, said matrixstructure is a construction wall, for example, a gypsum wallboard. Inyet another embodiment, the matrix structure comprises said PCM in fineparticle form coated on a paper or a plastic sheet.

In one embodiment, this invention also relates to a process forpreparing a matrix structure that has an improved ability to dampentemperature fluctuations, said process comprising contacting CPWBmicrostructures with a first absorbent material and incorporating saidPCM with the absorbent material to a matrix structure such as a wall. Ina second embodiment, the absorbent material is also added separately tothe matrix structure.

In one embodiment, the matrix structure the PCM described above is in anaqueous emulsion form or a powder form.

This invention also relates to a process for preparing a powder form ofPCM comprising CPWB microstructures, comprising the steps of:

-   -   (I) providing at least one PCM in aqueous wax emulsion form;    -   (II) subjecting said PCM to at least one powder-making process;        and    -   (III) optionally subjecting the resulting powder from step (II)        to a size reduction process;        -   wherein said emulsion is optionally subjected to additional            drying before, during, or after said at least one            powder-making process;        -   wherein said at least one powder-making process is selected            from the group consisting of freeze drying; lyophilization,            vacuum drying; air drying; spray drying; atomization;            evaporation; tray drying; flash drying; drum drying;            fluid-bed drying; oven drying; belt drying; microwave            drying; solar drying; linear combinations thereof; and            parallel combinations thereof;    -   (V) incorporating an absorbent material with the powder of step        (II).

This invention also relates to the powder prepared by the processdescribed above. In one embodiment, the powder form of PCM comprisesparticles in the average particle size range of from about 1 to about1000 micron. In another embodiment, said powder form of PCM comprisesparticles such that about 10%, 50% and/or 90% of the particles by weightare less than the average particle size within the range of from 1 to1000 micron. In yet another embodiment, said powder comprises dried 1-5mm chips.

BRIEF DESCRIPTION OF THE FIGURES

The disclosed aspects will hereinafter be described in conjunction withthe appended drawings, provided to illustrate and not to limit thedisclosed aspects, wherein like designations denote the elements.

FIG. 1 illustrates a simple schematic process describing the method ofthe present invention.

FIG. 2 illustrates a schematic describing the theoretical structure ofthe emulsified wax particle.

FIG. 3 relates to the DSC scan of a powder phase change material (PCM).

FIG. 4 relates to the DSC scan of a PCM in calcium carbonate.

FIG. 5 relates to the DSC scan of the PCM existing in an aqueousemulsion form.

FIG. 6 is a scanning electron micrograph of the nitrogen freezefractured wax emulsion.

FIG. 7 is a magnified image of the colloidally protected wax-basedmicrostructures.

FIG. 8 is a magnified image of the colloidally protected wax-basedmicrostructures.

DETAILED DESCRIPTION

The terms “approximately,” “about,” and “substantially,” as used herein,represent an amount close to the stated amount that still performs adesired function or achieves a desired result. For example, the terms“approximately,” “about,” and “substantially,” may refer to an amountthat is within less than 10% of, within less than 5% of, within lessthan 1% of, within less than 0.1% of, and within less than 0.01% of thestated amount.

Embodiments of the present disclosure provide a powder that is preparedfrom a wax based colloidal dispersion. The present invention alsorelates to methods for preparing powders from such wax based colloidaldispersions.

Definitions

For the purposes of this invention, a “colloidal dispersion” is adispersion of a discontinuous phase in a continuous phase.

By “wax” is meant any naturally occurring or synthetically occurringwax. It also includes blends or mixtures of one or more naturallyoccurring and/or synthetically occurring waxes. Those of animal origintypically consist of wax esters derived from a variety of carboxylicacids and fatty alcohols. The composition depends not only on species,but also on geographic location of the organism. Because they aremixtures, naturally produced waxes are softer and melt at lowertemperatures than the pure components.

By “wax-based colloidal dispersion” is meant an aqueous or non-aqueouscolloidally occurring dispersion or mixture that is in liquid or pastelike form comprising wax materials. A wax-based colloidal dispersion mayalso include the class of materials that are a suspension or othercolloidal mixture comprising wax. It may also include wax-basedemulsions.

By “wax-based emulsion” is meant an aqueous or non-aqueous, colloidallyoccurring dispersion or mixture in a liquid or paste-like formcomprising wax materials, which has both the discontinuous and thecontinuous phases as liquid. For example, an aqueous wax system caneither be a general colloid, or it can be an emulsion (which is a typeof colloid), depending on the melt temperature of the emulsified waxversus the use temperature.

By colloidally-protected wax-based (CPWB) microstructure is meant acolloidal dispersion or emulsion, wherein the continuous and thediscontinuous phase is liquid that is capable of phase change during themelting point transition of the core material. The microstructure iscolloidally protected with a wax or a lower fraction hydrocarbon core.The microstructure can exist in a dispersion or emulsion form or as apowder with reduced moisture or minimal moisture or no moisture.

Phase Change Materials

This invention relates to phase change materials (PCM) that comprisecolloidally protected wax-based microstructures. Colloidally protectedwax-based microstructures have a wax core and a casing of polymericmoieties which are adhered to the core via secondary forces such as VanDer Waals forces as opposed to a mechanical shell over a core in aclassical core-shell structure. Colloidally-protected wax-basedmicrostructures are described in detail below. The core may be fully orpartially encapsulated, in that the colloidal shell is not a physicalshell like a typical core-shell structure used in variety ofapplications including as PCMs.

The PCMs of the present invention are aqueous systems or dry systemswith minimal to zero moisture content. These PCMs may or may not beincorporated in a matrix for further use as phase change materials,where temperature fluctuations and heat absorption and desorption in aparticular narrow range are desired.

If the PCMs are aqueous systems, for example aqueous wax-based colloidaldispersions, the dry solids weight content of the colloidally-protectedwax-based microstructures in the matrix is from about 10% to about 60%by weight. Stated another way, the dry solids weight content of thecolloidally-protected wax-based microstructures by weight % of thematrix is any number from the following:

10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45,46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, and 60.

The dry solids weight content of the colloidally-protected wax-basedmicrostructures is also within a range defined by any two numbers above,including the endpoints of such a range.

If the PCMs are dry systems, for example, powder or particulate or chipform comprising colloidally-protected wax-based microstructures thathave been dried, the solids weight content of the colloidally-protectedwax-based microstructures in the matrix is from about 1% to about 50% byweight of the matrix. Stated another way, the dry solids weight contentof the colloidally-protected wax-based microstructures by weight percentof the matrix is any number from the following:

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, and 50.

The PCMs may not be entirely dry systems, and even after a drying step,some moisture or residual moisture may be present in the PCMs.

The dry solids weight content of the colloidally protected wax-basedmicrostructures is also within a range defined by any two numbers above,including the endpoints of such a range.

The polymers selected for the shell of the colloidally-protectedwax-based microstructures for PCM applications are one or more ofpolyvinyl alcohol and copolymers, cellulose ethers, polyethylene oxide,polyethyleneimines, polyvinylpyrrolidone, and copolymers, polyethyleneglycol, polyacrylamides and poly (N-isopropylamides), pullulan, sodiumalginate, gelatin, and starches.

The core of the colloidally-protected wax-based microstructures can be aparaffin wax that is a linear alkane with a general formula ofC_(n)H_(2n+2), wherein n varies from 13 to 80. The paraffin wax definedby n=13 is called tridecane and the one with n=80 is octacontane. Themelting point of C₁₃ wax is −5.4° C. Similarly, the melting point of theC₆₀ wax is 100° C. Similarly, the melting point of higher waxes (betweenC₆₀ and C₈₀) is higher than 100° C. but lower than the melting point ofthe colloidally-protective polymeric shell. Depending upon the narrowtemperature range in which the PCM is to be used, one could tailor acolloidally-protected wax-based microstructure with a specific wax corewithin it that melts and phase changes in that particular temperaturerange.

The temperature range in which the phase change is to be effected willdictate the wax that is to be used. To arrive at a specific temperaturerange within which the wax will melt can be determined by the carbonnumber of the wax, as well as the branching of the chains in the wax(branched structures). Some embodiments of the present inventionenvision wax that comprises branched structures as well as a blend ormixture of linear and branched structures of the wax. This inventionalso embodies mixtures or blends of waxes with two or more carbonnumbers that may either be linear, branched, or blends of linear andbranched structures. For example, a wax could be a mixture of C₁₅ linearand C₂₀ linear hydrocarbon alkane wax. In another example, the wax couldbe a mixture of C₁₆ linear and C₁₆ branched hydrocarbon alkane wax. Inyet another example, the wax could be a mixture of C₁₅ linear, C₁₆linear, and C₂₀ branched. In yet another example, the wax could be amixture of C₁₈ linear, C₁₈ branched.

Preferred paraffins or waxes include the C₁₄ to C₃₄ waxes. Furtherpreferred waxes are C₁₇ and C₁₈. In the table below are given themelting point and latent heat of fusion in kJ/kg of various paraffins orwaxes classified by their carbon numbers.

TABLE 1 Latent No. of Carbon Atoms Melting Point ° C. Heat of Fusion(kJ/kg) 14 5.5 228 15 10 205 16 16.7 237.1 17 21.7 213 18 28.0 244 1932.0 222 20 36.7 246 21 40.2 200 22 44.0 249 23 47.5 232 24 50.6 255 2549.4 238 26 56.3 256 27 58.8 236 28 61.6 253 29 63.4 240 30 65.4 251 3168.0 242 32 69.5 170 33 73.9 268 34 75.9 269

The temperature range in which the phase change materials can be used isfrom about −6° C. to about 140° C. Stated another way, the phase changematerials can be used at following temperatures measured in ° C.: −6,−5, −4, −3, −2, −1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28 29, 30, 31, 32,33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50,51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68,69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86,87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103,104, 105, 106, 107, 108, 109 110, 111, 112, 113, 114, 115, 116, 117,118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131,132, 133, 134, 135, 136, 137, 138, 139, and 140.

The temperature range in which the phase change materials can be used isalso defined by any two numbers above, including the endpoints of such arange.

For those waxes that melt at temperatures above 100° C., for example,C₆₀ (hexacontane) melts at 100° C., an aqueous dispersion can beprepared from such waxes by operating the dispersion preparation processunder pressure. Because water boils at higher temperature at pressuresgreater than 1 atmosphere, the high-pressure process enables makingcolloidally-protected wax-based dispersions and emulsions that melt attemperatures greater than 100° C. Once such colloidal dispersion isprepared, if the pressure is reduced before the lowering of temperature,the water will flash off, rendering particulate PCMs, for example inpowder form, or flakes, or chips. On the other hand, if the temperatureis lowered before the lowering of pressure, an aqueous system willresult that will have colloidally-protected wax-based microstructuresthat have a solidified core of the wax.

Clearly, the phase change of such materials will be effected only attemperatures higher than 100° C., and thus, one will have to contendwith evaporation of the aqueous phase when such PCMs are actually used.These aqueous PCMs with a wax core that melts at temperatures above theboiling point of water can be used under pressure higher than theatmospheric pressure.

For those waxes that melt at temperatures below 100° C., for example,C₃₀ (triacontane) melts at 66° C., an aqueous colloidal dispersion canbe prepared from such waxes by operating the dispersion preparationprocess at atmospheric pressure or partially reduced pressure. Aftersuch colloidally-protected wax-based aqueous dispersion is prepared, ifthe pressure is reduced further before the lowering of temperature, thewater will flash off, rendering particulate PCMs, for example in powderform, or flakes, or chips, with reduced or no moisture content. On theother hand, if the temperature is lowered before the lowering ofpressure, an aqueous system will result that will havecolloidally-protected wax-based microstructures that have solidifiedcore of the wax. Clearly, the phase change of such materials will beeffected around the melting point of the core wax.

Paraffin waxes that melt below and around the room temperature can betransformed into colloidally-protected wax-based microstructures at 1atmosphere pressure.

PCMs described herein have many advantages. They melt in the desiredoperating temperature range, have a high latent heat of fusion per unitvolume, high specific heat to provide additional heat storage, smallvolume change on phase transformation, small vapor pressure at operatingtemperature (in fact, minimal vapor pressure due to encapsulation in acolloidally protected microstructure), and congruent melting of the PCMfor constant storage capacity. Other properties include high nucleationrate to avoid supercoiling of the liquid phase and high crystal growthrate. Chemical properties of the PCMs include complete reversiblefreeze/melt no degradation after a large number of freeze/melt cycle, nocorrosiveness of the construction materials, non-toxicity, andnon-flammability.

In some examples, the PCM layer can be placed within wall constructionsto increase the thermal mass of the house. This invention also envisionssheets of paper or plastic (reinforced or otherwise) that can be coatedwith fine particles of the present PCMs. Thus the coated sheet acts as aPCM.

For example, a PCM layer can be placed within the wall close to theexternal layer in a wall application. During the day, the PCM layer willstore energy that flows into the wall. During night time, the PCM layerwill release the energy stored in the day, outside and inside thebuilding depending upon the insulation layers' positioning. The PCMlayer can be placed within the wall close to the external layer with aventilated air chamber. In other embodiments, the PCM layer can beplaced behind a glass and an air chamber. The PCM layer can be placedwithin wall constructions to increase ether thermal mass of the house.PCMs can also be used in ceilings. They can also be used in heatexchange and in hydraulic systems.

Waxes usable as core in the PCMs of the present invention are describedinfra.

Waxes

For the purposes herein, waxes include naturally occurring waxes andsynthetic waxes. Naturally occurring waxes include plant based waxes,animal waxes, and mineral waxes. Synthetic waxes are made by physical orchemical processes.

Examples of plant based waxes include mixtures of unesterifiedhydrocarbons, which may predominate over esters. The epicuticular waxesof plants are mixtures of substituted long-chain aliphatic hydrocarbons,containing alkanes, alkyl esters, sterol esters, fatty acids, primaryand secondary alcohols, diols, ketones, aldehydes, aliphatic aldehydes,primary and secondary alcohols, β-diketones, triacylglycerols, and manymore. The nature of the other lipid constituents can vary greatly withthe source of the waxy material, but they include hydrocarbons, Plantleaf surfaces are coated with a thin layer of waxy material. Specificexamples of plant wax include Carnauba wax, which is a hard wax obtainedfrom the Brazilian palm Copernicia prunifera, which contains the estermyricyl cerotate. Other plant based waxes include candelilla wax,ouricury wax, jojoba plant wax, bayberry wax, Japan wax, sunflower wax,tall oil, tallow wax, rice wax, and tallows.

Animal wax includes beeswax as well as waxes secreted by other insects.A major component of the beeswax used in constructing honeycombs is theester myricyl palmitate which is an ester of triacontanol and palmiticacid. Spermaceti occurs in large amounts in the head oil of the spermwhale. One of its main constituents is cetyl palmitate, another ester ofa fatty acid and a fatty alcohol. Lanolin is a wax obtained from wool,consisting of esters of sterols. Other animal wax examples includelanocerin, shellac, and ozokerite.

Examples of mineral waxes include montan wax, paraffin wax,microcrystalline wax and intermediate wax. Although many natural waxescontain esters, paraffin waxes are hydrocarbons, mixtures of alkanesusually in a homologous series of chain lengths. Paraffin waxes aremixtures of saturated n- and iso-alkanes, naphthenes, and alkyl- andnaphthene-substituted aromatic compounds. The degree of branching has animportant influence on the properties. Montan wax is a fossilized waxextracted from coal and lignite. It is very hard, reflecting the highconcentration of saturated fatty acids/esters and alcohols. Montan waxincludes chemical components formed of long chain alkyl acids and alkylesters having chain lengths of about 24 to 30 carbons. In addition,natural montan includes resin acids, polyterpenes and some alcohol,ketone and other hydrocarbons such that it is not a “pure” wax. Thesaponification number of montan, which is a saponifiable wax, is about92 and its melting point is about 80° C. In addition to montan wax,other naturally derived waxes are known for use in various industriesand include petroleum waxes derived from crude oil after processing,which include macrocrystalline wax, microcrystalline wax, petrolatum andparaffin wax. Paraffin wax is also a natural wax derived from petroleumand formed principally of straight-chain alkanes having average chainlengths of 20-30 carbon atoms.

Waxes comprising esters and/or acids may act as emulsifiers to theparaffins.

Synthetic waxes include waxes based on polypropylene, polyethylene, andpolytetrafluoroethylene. Other synthetic waxes are based on fatty acidamines, Fischer Tropsch, polyamides, polyethylene and relatedderivatives. Some waxes are obtained by cracking polyethylene at 400° C.The products have the formula (CH₂)_(n)H_(n+2), where n is about 50 toabout 100.

Also outside of the building products context, in addition to waxes thatoccur in natural form, there are various known synthetic waxes whichinclude synthetic polyethylene wax of low molecular weight, that is,molecular weights of less than about 10,000, and polyethylenes that havewax-like properties. Such waxes can be formed by direct polymerizationof ethylene under conditions suitable to control molecular weight.Polyethylenes with molecular weights in the range of from about 2,000 toabout 4,000 are waxes, and when in the range of from about 4,000 toabout 12,000 become wax resins.

Fischer-Tropsch waxes are polymethylene waxes produced by a particularpolymerization synthesis, specifically, a Fischer-Tropsch synthesis(polymerization of carbon monoxide under high pressure, high temperatureand special catalysts to produce hydrocarbon, followed by distillationto separate the products into liquid fuels and waxes). Such waxes(hydrocarbon waxes of microcrystalline, polyethylene and polymethylenetypes) can be chemically modified by, for example, air oxidation (togive an acid number of about 30 or less and a saponification number nolower than about 25) or modified with maleic anhydride or carboxylicacid. Such modified waxes are more easily emulsified in water and can besaponified or esterified. Other known synthetic waxes are polymerizedalpha-olefins. These are waxes formed of higher alpha-olefins of 20 ormore carbon atoms that have wax like properties. The materials are verybranched with broad molecular weight distributions and melting pointsranging about 54° C. to about 75° C. with molecular weights of about2,600 to about 2,800. Thus, waxes differ depending on the nature of thebase material as well as the polymerization or synthesis process, andresulting chemical structure, including the use and type of any chemicalmodification.

Various types of alpha-olefin and other olefinic synthetic waxes areknown within the broad category of waxes, as are chemically modifiedwaxes, and have been used in a variety of applications, outside thewater-resistant wallboard area. They are of a wide variety and vary incontent and chemical structure. As noted above, water-resistantwallboard products generally use paraffin, paraffin and montan, or otherparaffinic or synthetic waxes as described above in the mentionedexemplary patent references. While various waxes and wax substituteshave been used and tried in the building products area for wax emulsionsgenerally, particularly in some cases with a goal toward finding anadequate substitute for use of montan wax, the waxes as have beenadopted to date do not include normal alpha-olefin or oxidizedalpha-olefin waxes.

In one embodiment, the wax used for the preparation of the dispersion oremulsion is used in a micronized, pulverized form. U.S. Pat. Nos.8,669,401 and 4,846,887 show exemplary micronization processes. Boththese patents are incorporated by reference herein as if fully setforth.

This invention also relates to those paraffins or waxes that are liquidat room temperature but have sub-zero melting points. While the emulsionwould have colloidally-protected wax-based microstructures that have asolid shell and a liquid core, these materials could be used at sub-zerotemperatures to maintain temperatures through a heating and a coolingcycle. For example, the C₁₂ hydrocarbon dodecane melts at −10° C. andthe C₁₁ melts at −26° C. However, both are liquids at room temperature.One could use these materials to be emulsified with the polymericmaterials mentioned previously to form the colloidally-protected waxalkane hydrocarbon structures, which can then be dried at lowertemperatures or freeze dried to remove the water content and thenpowderized to now act as PCMs at sub-zero temperatures. These materialswould have applications in the medical field or even in the foodapplications where the temperatures need to be maintained at sub-zerobut without major fluctuations. Clearly, these materials cannot beclassified as waxes, but lower hydrocarbons. But these lowerhydrocarbons can also be emulsified and then rendered into powders tosub-zero usage as PCMs. Note that once the hydrocarbon alkane material,albeit in a liquid form, is trapped in the colloidally-protected form,when the water is removed, it will remain intact and not escape into thegaseous phase by evaporation (these are lighter fractions than waxes),colloidally protected by the secondary forces.

In one embodiment, the emulsifiers for this invention include montanwax, esters/acids, styrene-maleic anhydride, polyolefin maleicanhydride, or other anhydrides, carnauba wax, rice wax, sunflower wax.

Colloidally-Protected Wax Based Microstructures

Generally speaking, two scientific theories have been proposed toexplain the stability of colloidally-protected wax-based microstructuresthat comprise the PCMs described herein, namely, steric hindrance orelectrostatic repulsion. Applicants do not wish to be bound by thesetheories. Applicants believe their invention relates to wax-baseddispersions that may or may not relate to the two theories. It ispossible that one or both theories or neither of the two may explain thecolloidally-protected wax-based microstructures of the presentinvention.

In one embodiment, this invention relates to process for preparing PCMsin powder form. These PCMs in powder form are prepared from wax-baseddispersions. Various such emulsions and dispersions are described in theU.S. Pat. Nos. 8,748,516; 8,603,720; 8,424,243; 8,404,040; 8,382,888;8,252,106; 8,202,363 8,123,905; 8,486,377; 8,241,612; 8,741,056;8,541,350; 8,476,345; and 8,123,905.

In another embodiment, this invention further relates to process forpreparing PCMs in powder form from wax-based dispersions. Various suchemulsions and dispersions are further described in the InternationalPatent App. Nos. PCT/US2014/040559 and PCT/US2014/38244; ProvisionalPatent App. Nos. 61/914,850, 61/942,490, 61/946,396, and 61/953,640;U.S. patent application Ser. No. 14/278,919; U.S. patent applicationSer. No. 14/293,650 (US Patent Pub. No. 20140352866); U.S. ProvisionalPatent App. Nos. 61/914,850, 61/942,490, 61/946,396, and 61/953,640;20140047998; 20140245928; 20140105945; 20140105845; 20130136855;20130108882; 20130042792; 20130330526; 20130224395; 20130183533;20130035430; 20130344434; 20130305962; 20130273472; and 20130136935. Theabove patents and patent applications are incorporated by reference asif they are fully set forth herein. The purpose for listing thesepatents and patent applications is to provide exemplary wax-basedcolloidal dispersion formulations and compositions that are amenable tothe powderization process described herein, that result incolloidally-protected wax-based microstructures that comprise the PCMsof the present invention. For example, the following patent referencesdescribe wax-based emulsions. These references are set forth as if fullincorporated herein.

Several wax emulsion formulations are disclosed in U.S. Pat. No.5,437,722, which are incorporated by reference herein. It describes awater-resistant gypsum composition and wax emulsion therefore, whichincludes a paraffin hydrocarbon having a melting point of about 40° C.to 80° C., about 1 to 200 parts by weight montan wax per 100 parts ofthe paraffin hydrocarbon, and about 1 to 50 parts by weight polyvinylalcohol per 100 parts of the paraffin hydrocarbon.

U.S. Patent Pub. No. 2006/0196391 describes use of triglycerides inemulsions, and notes that the prior art has made use of petroleum waxesand synthetic waxes such as Fischer Tropsch and polyethylene waxes,which have been used for purposes similar to those of the invention ofU.S. Patent Pub. No. 2006/0196391 with mixed results.

In the building products area, U.S. Patent Pub. No 2007/0181035 A1 isdirected to a composition for use in making medium density fiberboard(MDF). The composition has a component for reducing surface tension andimproving dimensional stability for use in oriented strand board andMDF. The surface tension agents are either fluorinated hydrocarboncompounds of two to six carbons or alkoxylates of alkyl phenols oralkylated acetylene diols. These materials are provided to a compositionhaving a combination of montan wax with other waxes, ammonium hydroxidefor saponification, water and polyvinyl alcohol. Nonsaponifiable waxesmay be used in this composition, including paraffin and scale or slackwax (which is petroleum derived). Saponifiable waxes which may be usedinclude Montan, petroleum wax, and various natural waxes.

U.S. Patent Pub. No. 2007/0245931 A1 discloses use of alkyl phenols inemulsions for water-proof gypsum board. The alkyl phenols are long-chainhydrocarbon chains having a phenolated ring of 24-34 carbon chainlengths. The publication describes use of lignosulfonic acid, andmagnesium sulfate. The wax components can be combinations of paraffinand montan. The patent claims that the compositions are stable withoutthe use of starch as in prior U.S. Pat. No. 6,663,707 of the sameinventor. The wax used in the composition may be various commerciallyknown waxes having a melting point of from about 120° F. (48.9° C.) to150° F. (65.6° C.) with low volatility and a high molecular weight withcarbon chain lengths of 36 or higher. The hydrocarbon wax componentincludes waxes known in the field of gypsum slurries.

U.S. Pat. No. 6,890,976 describes an aqueous emulsion for gypsumproducts with hydrocarbon wax, polyolefin-maleic anhydride graft polymerand polyvinyl alcohol and/or acetate. The maleic-modified material isknown as FLOZOL®. The hydrocarbon wax can be paraffin or a polyethylenewax, maleated hydrocarbon wax or combinations thereof. The wax can alsobe a synthetic wax ester or an acid wax. The polyolefin-maleic anhydridegraft copolymer is a 50-500 carbon chain graft copolymer, which whenprovided to the wax emulsion is described as providing improved waterrepellency to a final gypsum product.

U.S. Patent Publication No. 2004/0083928 A1 describes a suspension,instead of an emulsion, of various waxes in water that is mixed directlywith gypsum. In describing the waxes, the suspensions can includepolyethylene wax, maleated hydrocarbons and other waxes as well as waxcombinations.

U.S. Pat. No. 7,192,909 describes use of polyolefin wax in anapplication outside the building products area, which is as a lubricantfor plastics processing, specifically for PVC. The waxes are describedas homopolymers and copolymers of various alpha-olefins that have beenmodified in a polar manner (oxidized) or grated with polar reagents.They can be used alone or in combination with other waxes, e.g. montanwaxes, fatty acid derivatives or paraffins.

As described in FIG. 1, in the first step, a colloidally-protected waxbased microstructures in a dispersion or emulsion are prepared. Thedispersion or emulsion is prepared according to the specification fortheir use in variety of applications. For a general understanding of themethod of making the exemplary wax emulsion, reference is made to theflow diagram in FIG. 1. As shown in 101, first the wax components may bemixed in an appropriate mixer device. Then, as shown in 102, the waxcomponent mixture may be pumped to a colloid mill or homogenizer. Asdemonstrated in 103, in a separate step, water, and any emulsifiers,stabilizers, or additives (e.g., ethylene-vinyl alcohol-vinyl acetateterpolymer) are mixed. Then the aqueous solution is pumped into acolloid mill or homogenizer in 104. Steps 101 and 103 may be performedsimultaneously, or they may be performed at different times. Steps 102and 104 may be performed at the same time, so as to ensure properformation of droplets in the emulsion. In some embodiments, steps 101and 102 may be performed before step 103 is started. Finally, as shownin 105, the two mixtures from 102 and 104 are milled or homogenized toform an aqueous wax-based emulsion.

In the next step, if the said colloidally-protected wax-basedmicrostructures are desired in a dry powder form, then said dispersionor emulsion is subjected to the drying and powderization step. Dryingcan be accomplished by one or more of the known drying methods such asfreeze drying, vacuum drying, air drying, spray drying, atomization,evaporation, tray drying, flash drying, drum drying, fluid-bed drying,oven drying, belt drying, microwave drying, lyophilization, and solardrying. Other known drying methods that may not be listed herein, mayalso be used. In one embodiment, more than one method may be used to drythe colloidal dispersion.

Further as shown in FIG. 1, in the third step, optionally, the moisturecontent of the powder material may be adjusted to suit the use of thepowder in a particular application. In the next step, which also is anoptional step, the powder may be subjected to a further pulverizationprocess to provide for a specific particle size distribution of thepowder. Finally, the resulting powder is then blended with a basematerial to improve the properties of the base material, for example,its ability to dampen temperature fluctuations as well as, or in thealternative, its moisture repellency.

The powder resulting from step 2 in the process described above, mayhave an average particle size in the range of from about 0.1 micron toabout 1,000 micron. Clearly, the larger sized particles would beagglomerates of the smaller powder emulsion particles. Theoretically,the smallest particle will be a wax particle that is covered, forexample, by a hydrogen-bonded coating of stabilizing polymeric chainsof, for example, among other things, polyvinyl alcohol and copolymers,cellulose ethers, polyethylene oxide, polyethyleneimines,polyvinylpyrrolidone, and copolymers, polyethylene glycol,polyacrylamides and poly (N-isopropylamides, pullulan, sodium alginate,gelatin, and starches.

The average particle size of the PCM powders of the present inventioncan be any one of the following average particle sizes, measured inmicrons:

0.1, 0.2, 0.4, 0.6, 0.8, 1, . . . , 2, 3, 4, 5, 6, 7, 8, 9, . . . , 98,99, 100, 101, 102, . . . , 198, 199, 200, 201, 202, . . . , 298, 299,300, 301, 302, . . . , 398, 399, 400, 401, 402, . . . , 498, 499, 500,501, 502, . . . , 598, 599, 600, 601, 602, . . . , 698, 699, 700, 701,702, . . . , 798, 799, 800, 801, 802, . . . , 898, 899, 900, 901, 902, .. . , 998, 999, and 1000.

The average particle size can also be in a range that is determined byany two numbers recited above, which would include the endpoints of therange.

Alternatively, the colloidal dispersions, including the emulsions, canbe dried into about 1 to about 5 mm chips, which could be regular shapedor irregular shaped. Clearly such chips would be loose agglomeration ofthe colloidally dispersed or emulsified particles.

In one embodiment, the particle size of the powders of the presentinvention is also such that about 10%, about 50% and/or about 90% of theparticles by weight are less than the following average particle size,measured in microns:

1, 2, 3, 4, 5, 6, 7, 8, 9, . . . , 98, 99, 100, 101, 102, . . . , 198,199, 200, 201, 202, . . . , 298, 299, 300, 301, 302, . . . , 398, 399,400, 401, 402, . . . , 498, 499, 500, 501, 502, . . . , 598, 599, 600,601, 602, . . . , 698, 699, 700, 701, 702, . . . , 798, 799, 800, 801,802, . . . , 898, 899, 900, 901, 902, . . . , 998, 999, and 1000.

The average particle size can also be in a range that is determined byany two numbers recited above, which would include the endpoints of therange.

Alternatively, the colloidal dispersions, including the emulsions, canbe dried into 1-5 mm chips, which could be regular shaped or irregularshaped. Clearly such chips would be agglomeration of the colloidallydispersed or emulsified particles. Such chips could be of the followingaverage particle size: 1, 1.5, 2, 2.5, 3, 3.5, 4. 4.5, and 5 mm. Suchchips could also be within the range formed by any two numbers of thislist including the end-points of such a range.

FIG. 2 describes the particle model of a unitary wax particle that hasbeen stabilized in the colloidal dispersion. Applicants do not wish tobe bound by the theory of the unitary wax particle stabilized in thedispersion. According to this model, a wax particle is tethered toanother wax particle, for example, paraffin wax and montan waxrespectively. The montan wax is then tethered to polyvinyl alcohol. Themolecular level attraction between the wax and montan wax, and the PVOHwith both montan and paraffin wax, is secondary in nature as opposed toionic or covalent chemical bonds.

The first mechanism by which many of the wax emulsions (colloidaldispersions) are stabilized is the steric hindrance mechanism. Accordingto this mechanism, high molecular weight polymers (e.g. PVOH) aretethered to the outer surface of a wax particle and surround it. Due tosteric hindrance, the PVOH molecules surrounding each wax particle thenprevent adjacent wax particles from coalescing.

Alternatively, electrostatic repulsion helps with the stabilization ofthe colloidal dispersions. In this mechanism, the wax particle, whichcontains acid or ester groups (either inherently or mixed in), is firstsaponified with a base, converting the acid or ester groups tonegatively charged carboxylate moieties. Because of their polar nature,these negatively charged carboxylate moieties exist at the water/waxinterface, giving the wax particle a net negative charge. These negativecharges on adjacent wax particles then constitute a repulsive forcebetween particles that effectively stabilizes the dispersion (emulsion).

Thus, according to one model, as shown in FIG. 2, a wax particle isenclosed in a “web” of PVOH polymeric chains. This is not akin to ashell of a core-shell particle, but the PVOH loosely protects(colloidally protects) the wax particle. One could envision the waxparticle as a solid ball or a nucleus surrounded by polymeric chainslike strings. While the polymer does not form a shell like physicalcasing, the casing herein is based on secondary forces of attraction,e.g., Van der Waals forces. Hydrogen bonding may also be one of theforces for the encapsulation of the PVOH of the wax particles.Applicants do not wish to be bound by this theory. However, the modeldoes explain the wax particle with the PVOH casing over it. In the aboveexamples, PVOH is sued as an exemplary polymeric system. However, otherpolymeric systems sued herein, or their combinations can also be used toprepare the colloidally-protected wax-based microstructures.

In one embodiment, the model shown in FIG. 2 describes a wax-baseddispersion or wax-based emulsion or a dispersion or emulsion ofcolloidally-protected wax-based microstructures from which a powder ismade. Such powder, still a colloidally-protected wax-basedmicrostructures is used as a phase change material. A phase-changematerial (PCM) is a substance with a high heat of fusion which, meltingand solidifying at a certain temperature, is capable of storing andreleasing large amounts of energy. Heat is absorbed or released when thematerial changes from solid to liquid and vice versa; thus, PCMs areclassified as latent heat storage (LHS) units. The phase change hereinwould be the solid-liquid phase change. Depending on the molecularweight and the type of wax material used, one could tailor the phasechange for various temperatures. U.S. Pat. No. 6,939,610 describes phasechange materials. This patent is incorporated by reference as if fullyset forth herein.

According to one theory, which the Applicants do not wish to be boundby, the polymeric chains surrounding the wax particle colloidallyprotect the wax particle such that even with the phase change from solidto liquid of the wax, the liquefied wax does not “bleed” out frombetween the polymeric chains or polymeric chain clusters. This is as aresult of secondary Van der Waals forces, and/or surface tension. So,while it could be argued that the colloidal protection is not physicallyencapsulating, for all practical purposes, it is, in that the surfacetension will not permit the wax to ooze out or bleed out through thepolymeric shell.

Absorbent Materials

Alternatively, it is possible that the surface tension of the paraffinmay be sufficiently low for the surface tension of the PVOH to retainand hold the paraffin within the PVOH encapsulated film, and some amountof paraffin may “bleed” out and into the matrix in which such PCMs basedon the colloidally protected wax-based microstructures are used. In oneembodiment, the present invention relates to adding absorbent oradsorbent materials to the matrix in which such materials are used, toabsorb the residual or leaked paraffin or wax from within the polymericfilm, for example, that of PVOH. In another embodiment, such absorbentmaterials are used with the CPWB to form the phase change materials.

Such absorbent or adsorbent materials include for example, activatedcarbon, graphite, bentonite, deposited carbon, silica gel, activatedalumina, zeolites, molecular sieves, alkali metal alumino-silicate,silica-magnesia gel, silica-alumina gel, activated alumina, calciumoxide, calcium carbonate, clay, diatomaceous earth, cyclodextrin, or acombination thereof. Activated carbon includes powdered carbon andgranular activated carbon (activated charcoal). Granular activatedcarbon is an adsorbent derived from carbonaceous raw material, in whichthermal or chemical means have been used to remove most of the volatilenon-carbon constituents and a portion of the original carbon content,yielding a structure with high surface area. The resulting carbonstructure may be a relatively regular network of carbon atoms derivedfrom the cellular arrangement of the raw material, or it may be anirregular mass of crystallite platelets, but in either event thestructure will be laced with openings to appear, under electronmicrographic magnification, as a sponge like structure. The carbonsurface is characteristically non-polar, that is, it is essentiallyelectrically neutral. This non-polarity gives the activated carbonsurface high affinity for comparatively non-polar adsorbates, includingmost organics.

Activated carbon is a highly porous, amorphous solid consisting ofmicrocrystallites with a graphite lattice, usually prepared in smallpellets or a powder. Activated carbon can be manufactured fromcarbonaceous material, including coal (bituminous, subbituminous, andlignite), peat, wood, or nutshells (e.g., coconut). The manufacturingprocess consists of two phases, carbonization and activation. Thecarbonization process includes drying and then heating to separateby-products, including tars and other hydrocarbons from the rawmaterial, as well as to drive off any gases generated. The process iscompleted by heating the material over 400° C. (750° F.) in anoxygen-free atmosphere that cannot support combustion. The carbonizedparticles are then “activated” by exposing them to an oxidizing agent,usually steam or carbon dioxide at high temperature. This agent burnsoff the pore blocking structures created during the carbonization phaseand so, they develop a porous, three-dimensional graphite latticestructure. The size of the pores developed during activation is afunction of the time that they spend in this stage. Longer exposuretimes result in larger pore sizes. The most popular aqueous phasecarbons are bituminous based because of their hardness, abrasionresistance, pore size distribution, and low cost, but theireffectiveness needs to be tested in each application to determine theoptimal product.

Table A below provides various grades of powdered carbon from the AsburyGraphite Mills Inc., Asbury, N.J.

TABLE A Pore Surface Type of Volume Pore Size Area Carbon Grade (cc/gm)(nanometers) (m²/gm) Molasses # Iodine # Particle Size Coconut 5562 n/a≤2   1000 n/a 1100 90% -200 mesh Coal 5583 0.8 2-50 600 200-250 600 90%-325 mesh Wood 5597 1.8 50+ 1200  70-190 1070 90% -325 mesh

Table B below provides various grades of granular activated carbon fromthe Asbury Graphite Mills Inc., Asbury, N.J.

TABLE B Pore Surface Volume Mesh Area Type of Carbon Grade (cc/gm) Size(m²/gm) Hardness % Molasses # Iodine # Lignite 5506 .95 12 × 20 650 7085 575 Coal 5589 .80 12 × 40 900 90 40 900 Coconut 5586S n/a 12 × 401100 98 n/a 1100

In one embodiment, this invention also relates to a process forpreparing a matrix structure that has an improved ability to dampentemperature fluctuations, comprising contacting PCM comprising CPWBmicrostructures with an absorbent material and incorporating said PCMwith the absorbent material to a matrix structure such as a wall. In asecond embodiment, the absorbent material is added separately to thematrix structure.

The CPWB microstructures can be contacted (for example, mixed) with theabsorbent material when the CPWB microstructures are in an emulsion formor are in a powder form. In one embodiment as described infra in theexperimental section, a paste or a coating is prepared comprising thewax emulsion and the absorbent material such as the activated carbon.Other ingredients included in the paste or the coating include one ormore of thickeners, fillers, rheology modifiers, stabilizers, etc.

By “matrix” materials or structure is meant any object that requirestemperature fluctuation dampening. Various examples of such matrixstructures are given below, for example, fuel tanks, batteries, panels,wall-boards, wall panelings, walls, etc. By “incorporation” is meantclosely contacting the PCM with the matrix. Such “incorporation”includes mixing, coating, paste formation, PCM coatings on paper/plasticsheets for further inclusions for example in wall-boards, and otherphysical inclusions of the PCM in the matrix.

The powder form of the colloidally protected wax based microstructuresallows for easy addition to base materials or matrix materials for avariety of applications. In one embodiment, the activated carbon isadded to the PCM after conversion to a powder form.

Some potential PCM applications include wax-based emulsion or dispersionas coating formulations for fuel tanks in space vehicles, or for thespace craft as a whole. See for example U.S. Patent App. No.2008/0005052 which is incorporated by reference herein. The powders ofthe present invention potentially can be blended with high temperatureorganic resins (such as silicone resins) to provide high temperatureheat sinks. In another example, high temperature has a disastrous effecton the longevity of batteries in electric vehicles (Tesla, Nissan Leaf,Prius, etc.). PCMs are used to address this issue. See for examplehttp://chargedevs.com/features/allcell-technologies %E2%80%99-new-phase-change-thermal-management-material/.

Other applications include thermal insulating coating for aircrafts, seefor example U.S. Pat. No. 6,939,610, which is also incorporated byreference herein.

The PCMs described herein can also be used in the polyurethane OEMapplication for spray foam. The R value of the foam should improve oncethe powder is added. In one embodiment, only a coating is developed thatwill be first applied unto a substrate (e.g., directly onto the atticframe) and then followed with a spray of regular insulating foam. TheR-value of the system should then be much improved than just the PU foamalone.

In consumer products, where the outside case becomes too hot, the PCMpowder described herein can be applied as a coating to the inside of theouter casing, thus keeping the outer casing cool even when the waterinside is boiling, e.g., a safety kettle. Other applications includeAstroTurf (Astroturf: http://www.microteklabs.com/field-turfhtml) andcoatings for military desert tents, military hardware etc.

Other applications include automotives such as batteries and vehiclecoatings; interior coatings in airplanes and space vehicles; in buildingand construction industry; consumer products such as pizza deliverycoffee making, etc.; and in non-washable fabrics such as tents andfabrics. PCMs of the present invention can also be used for smarttextiles. See S. Mondal, Phase change materials for smart textiles—Anoverview, Appl. Therm. Eng. (2007),doi:10.1016/j.applthermaleng.2007.08.009. This scholarly paper isarticulated by reference herein.

In other words, in all applications paraffin-based encapsulated PCMs areused today, the present invention provides a powder of wax particlesthat are colloidally-protected in a casing by polymeric moieties such asPVOH that proves the same functionality using a variety of melt pointparaffins.

A report from the U.S. Department of Energy under the BuildingTechnology Program, by Jan Kosny, Nitin Shukla, and Ali Fallahi, titled,“Cost Analysis of Simple Phase-Change Material-Enhanced BuildingEnvelopes describe various applications of the PCMs in buildingtechnology and construction (published in January 2013, availableelectronically at http://www.osti.gov/bridge—NREL Contract No.DE-AC36-08G028308). This reference is incorporated herein as if setforth fully.

PCMs of the present invention can also be used in building applicationsfor under-the-floor applications, in air exchanger applications, and ascomponents of a wall. Other applications include encapsulation of thePCMs of the present invention in plastic or metal packaging aluminum orsteel, for example). PCMs can also be used for impregnation of porousmaterials as panel board and concrete.

An exemplary wax-based colloidal dispersion system is described herein,which can be rendered into the embodiment of the present invention, thatis, a dried emulsified powder that retains some level of chemical aswell as structural attributes of the colloidally dispersed (emulsified)particles.

Colloidally-Protected Microstructures Including Moisture ResistantStabilizers

Exemplary colloidally-protected wax-based microstructures for use in,for example, a water-resistant joint compound are now described ingreater detail, as follows. The wax-based emulsion can be spray driedinto a powder form for subsequent use to be blended with joint compoundin building construction to impart water resistance and temperaturedampening effect.

In one embodiment, the wax emulsion may comprise water, a base, one ormore waxes optionally selected from the group consisting of slack wax,montan wax, and paraffin wax, and a polymeric stabilizer, such asethylene-vinyl alcohol-vinyl acetate terpolymer or polyvinyl alcohol.Further, carnauba wax, sunflower wax, tall oil, tallow wax, rice wax,and any other natural or synthetic wax or emulsifier containing organicacids and/or esters can be used to form the wax emulsion. Generally, thewax emulsion may be used in the manufacture of composite wallboard. Butin this case, the wax emulsion is further subjected to a powder-makingstep.

In another embodiment, the wax emulsion may comprise water, paraffinwax, polyvinyl alcohol, and an acid or ester thereof and optionally oneor more of a base, preservative, dispersant, defoamer, thickener, orbinder.

In a further embodiment, the wax emulsion may comprise water, paraffinwax, polyvinyl alcohol, activated carbon, and an acid or ester thereofand optionally one or more of a base, preservative, dispersant,defoamer, thickener, or binder.

In another embodiment, the wax emulsion may comprise water, paraffinwax, polyvinyl alcohol, and montan wax or a fatty acid or ester thereofand optionally one or more of a base, preservative, dispersant,defoamer, thickener, or binder. In one example, the fatty acid isstearic acid.

In still a further embodiment, the wax emulsion may comprise water,paraffin wax, polyvinyl alcohol, activated carbon, and montan wax or afatty acid or ester thereof and optionally one or more of a base,preservative, dispersant, defoamer, thickener, or binder.

Water may be provided to the emulsion, for example in amounts of about30% to about 60% by weight of the emulsion. The solids content of thewax emulsion is preferably about 40% to about 70% by weight of theemulsion. Other amounts may be used.

A dispersant and/or a surfactant may be employed in the wax emulsions.Optional dispersants, include, but are not limited to those having asulfur or a sulfur-containing group(s) in the compound such as sulfonicacids (R—S(═O)₂—OH) and their salts, wherein the R groups may beotherwise functionalized with hydroxyl, carboxyl or other useful bondinggroups. In some embodiments, higher molecular weight sulfonic acidcompounds such as lignosulfonate, lignosulfonic acid, naphthalenesulfonic acid, sulfonate salts of these acids and derivatized orfunctionalized versions of these materials are used in addition orinstead. An example lignosulfonic acid salt is Polyfon® H available fromMeadWestvaco Corporation, Charleston, S.C. Other dispersants may beused, such as sodium polyacrylate (Darvan® 811 reagent), magnesiumsulfate, polycarboxylate technology, ammonium hepta molybdate/starchcombinations, non-ionic surfactants, ionic surfactants, zwitterionicsurfactants and mixtures thereof, alkyl quaternary ammoniummontmorillonite clay, etc. Similar materials may also be used, wheresuch materials may be compatible with and perform well with theformulation components. In certain embodiments, the emulsions containabout 0 to about 5% by weight of the dispersant. In other embodiments,the emulsions contain about 1 to about 3% by weight of the dispersant.

One or more preservative may be included in the wax emulsion. Usefulpreservatives comprise thiazoline-3-one compounds. Examples of suchpreservatives include those containing one or more of5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothazolin-3-one,1,2-benzisothiazolin-3-one, diuron, 3-iodo-2-propynyl butylcarbamate, or2-N-octyl-4-isothiazolin-3-one. Products containing useful preservativesinclude, without limitation, the Acticide® CMB 2 and MKW2 products. Incertain embodiments, the emulsions contain about 0.05 to about 5% byweight of the preservatives. In other embodiments, the emulsions containabout 0.5 to about 2% by weight of the preservatives.

In other embodiments, a binder is included in the wax emulsion. Usefulbinders accordingly contain an acrylic polymer such as the Acronal® NX4787 product. In certain embodiments, the emulsions contain about 1 toabout 30% by weight of the binder. In other embodiments, the emulsionscontain about 5 to about 15% by weight of the binder. In furtherembodiments, the emulsions contain about 7 to about 12% by weight of thebinder.

The wax emulsion may further include other additives, including withoutlimitation additional emulsifiers and stabilizers typically used in waxemulsions, flame retardants, lignocellulosic fungicides, insecticides,biocides, waxes, sizing agents, fillers, additional adhesives and/orcatalysts. Such additives are preferably present in minor amounts andare provided in amounts which will not materially affect the resultingcomposite board properties.

Preferably no more than 30% by weight, more preferably no more than 10%,and most preferably no more than 5% by weight of such additives arepresent in the wax emulsion.

In one embodiment, a dispersant and/or surfactant may comprise about0.01% to about 5.0% by weight of the wax emulsion formulationcomposition, preferably about 0.1% to about 2.0% by weight of the waxemulsion formulation composition. Other concentrations may be used.

The wax component of the emulsion may include at least one wax which maybe slack wax, or a combination of montan wax and slack wax. The totalwax content may be about 30% to about 60%, more preferably about 30% toabout 40% by weight of the emulsion. Slack wax may be any suitable slackwax known or to be developed which incorporates a material that is ahigher petroleum refining fraction of generally up to about 20% byweight oil. In addition to, or as an alternative to slack wax, paraffinwaxes of a more refined fraction are also useful within the scope of theinvention.

Suitable paraffin waxes may be any suitable paraffin wax, and preferablyparaffins of melting points of from about 20° C. to about 110° C.,although lower or higher melting points may be used if drying conditionsare altered accordingly using any techniques known or yet to bedeveloped in the composite board manufacturing arts or otherwise. Thus,petroleum fraction waxes, either paraffin or microcrystalline, and whichmay be either in the form of varying levels of refined paraffins, orless refined slack wax may be used. Optionally, synthetic waxes such asethylenic polymers or hydrocarbon types derived via Fischer-Tropschsynthesis may be included in addition or instead, however paraffins orslack waxes are preferred in certain embodiments. The wax emulsion usedin the joint compound can be formed from slack wax, montan wax, paraffinwax, carnauba wax, tall oil, sunflower wax, rice wax, and any othernatural or synthetic wax containing organic acids and/or esters, orcombinations thereof. In some embodiments, the synthetic wax used in theemulsion may comprise ethylenic polymers or hydrocarbon types,optionally derived via Fischer-Tropsch synthesis, or combinationsthereof. In other embodiments, the synthetic wax is a paraffin wax witha transition temperature of about 20° C. such as comprisingn-heptadecane (Rubitherm® RT21). In further embodiments, the syntheticwax is a paraffin wax with a transition temperature of about 28° C. suchas those comprising n-octadecane (Rubitherm® RT28). In yet otherembodiments, the synthetic wax is a mixture of octadecane and eicosane(Saraphaez® 20 and Parafol® 18-97).

Optionally, the synthetic waxes can be added in concentrations rangingfrom about 0.1% to about 8% of the dry weight of the joint compound orfrom about 0.5% to about 4.0% of the dry weight of the joint compound.In some embodiments, the wax emulsion is stabilized by polyvinylalcohol.

Montan wax, which is also known in the art as lignite wax, is a hard,naturally occurring wax that is typically dark to amber in color(although lighter, more refined montan waxes are also commerciallyavailable). Montan is insoluble in water, but is soluble in solventssuch as carbon tetrachloride, benzene and chloroform. In addition tonaturally derived montan wax, alkyl acids and/or alkyl esters which arederived from high molecular weight fatty acids of synthetic or naturalsources with chain lengths preferably of at least about 18 carbons, morepreferably from 26 to 46 carbons that function in a manner similar tonaturally derived montan wax are also within the scope of the inventionand are included within the scope of “montan wax” as that term is usedherein unless the context indicates otherwise (e.g., “naturallyoccurring montan wax”). Such alkyl acids are generally described asbeing of formula R—COOH, where R is an alkyl non-polar group which islipophilic and can be from about 18 to more than 200 carbon atoms. Anexample of such a material is stearic acid octacosanoic acid and itscorresponding ester which is, for example, a di-ester of that acid withethylene glycol. The COOH group forms hydrophilic polar salts in thepresence of alkali metals such as sodium or potassium in the emulsion.While the alkyl portion of the molecule gets embedded within theparaffin, the acid portion is at the paraffin/aqueous medium interface,providing stability to the emulsion.

In some embodiments, the at least one wax component of the emulsionincludes primarily and, preferably completely a slack wax component. Insome embodiments, the at least one wax component is made up of acombination of paraffin wax and montan wax or of slack wax and montanwax. Although it should be understood that varying combinations of suchwaxes can be used. When using montan wax or a related alkyl acids oresters thereof in combination with one or more of the other suitable waxcomponents, it is preferred that they be present in an amount of about0.1% to about 10%, more preferably about 1% to about 4% by weight of thewax emulsion with the remaining wax or waxes present in amounts of fromabout 30% to about 50%, more preferably about 30% to about 35% by weightof the wax emulsion.

In some embodiments, the wax emulsion includes polyvinyl alcohol (PVOH)of any suitable grade which is at least partially hydrolyzed. Thepreferred polyvinyl alcohol is at least about 80%, and more preferablyat least about 90%, and most preferably about 97 to about 100%hydrolyzed polyvinyl acetate. Suitably, the polyvinyl alcohol is solublein water at elevated temperatures of about 60° C. to about 95° C., butinsoluble in cold water. The hydrolyzed polyvinyl alcohol is included inthe emulsion in an amount of up to about 10% by weight. In certainembodiments, the polyvinyl alcohol is present in the emulsion in anamount of about 0.5% to about 10% by weight of the emulsion. In otherembodiments, the polyvinyl alcohol is present in the emulsion in anamount of about 0.1% to about 5% by weight of the emulsion. In furtherembodiments, the polyvinyl alcohol is present in the emulsion in anamount of about 2% to about 3% by weight of the wax emulsion.

In some embodiments, the stabilizer comprises a polymer that is capableof hydrogen bonding to the carboxylate or similar moieties at thewater/paraffin interface. Polymers that fit the hydrogen-bondingrequirement would have such groups as hydroxyl, amine, and/or thiol,amongst others, along the polymer chain. Reducing the polymer's affinityfor water (and thus, its water solubility) could be achieved byinserting hydrophobic groups such as alkyl, alkoxy silanes, or alkylhalide groups into the polymer chain. The result may be a polymer suchas ethylene-vinyl acetate-vinyl alcohol terpolymer (where the vinylacetate has been substantially hydrolyzed). The vinyl acetate contentmay be about 0% to about 15%. In some embodiments, the vinyl acetatecontent is about 0% to about 3% of the terpolymer chain. Theethylene-vinyl alcohol-vinyl acetate terpolymer may be included in theemulsion in an amount of up to about 10.0% by weight, preferably about0.1% to about 5.0% by weight of the emulsion. In some embodiments,ethylene-vinyl alcohol-vinyl acetate terpolymer may be included in theemulsion in an amount of about 2% to about 3% by weight of the waxemulsion. An example ethylene-vinyl alcohol-vinyl acetate terpolymer isthe Exceval AQ4104™, available from Kuraray Chemical Company.

The wax emulsion may include a stabilizer material (e.g., PVOH,ethylene-vinyl alcohol-vinyl acetate terpolymer as described above). Thestabilizer may be soluble in water at elevated temperatures similar tothose disclosed with reference to PVOH (e.g., about 60° C. up to about95° C.), but insoluble in cold water. The active species in the waxcomponent (e.g., montan wax) may be the carboxylic acids and esters,which may comprise as much as about 90% of the wax. These chemicalgroups may be converted into carboxylate moieties upon hydrolysis in ahigh pH environment (e.g., in an environment including aqueous KOH). Thecarboxylate moieties may act as a hydrophilic portion or “head” of themolecule. The hydrophilic portions can directly interface with thesurrounding aqueous environment, while the rest of the molecule, whichmay be a lipophilic portion or “tail”, may be embedded in the wax.

A stabilizer capable of hydrogen bonding to carboxylate moieties (e.g.,PVOH or ethylene-vinyl alcohol-vinyl acetate terpolymer as describedabove) may be used in the wax emulsion. The polar nature of thecarboxylate moiety may offer an optimal anchoring point for a stabilizerchain through hydrogen bonding. When stabilizer chains are firmlyanchored to the carboxylate moieties as described above, the stabilizermay provide emulsion stabilization through steric hindrance. Inembodiments where the wax emulsion is subsequently dispersed in awallboard (e.g., gypsum board) system, all the water may be evaporatedaway during wallboard manufacture. The stabilizer may then function as agate-keeper for repelling moisture. Decreasing the solubility of thestabilizer in water may improve the moisture resistance of the waxemulsion and the wallboard. For example, fully hydrolyzed PVOH may onlydissolve in heated, and not cool, water. For another example,ethylene-vinyl alcohol-vinyl acetate terpolymer may be even less watersoluble than PVOH. The ethylene repeating units may reduce the overallwater solubility. Other stabilizer materials are also possible. Forexample, polymers with hydrogen bonding capability such as thosecontaining specific functional groups, such as alcohols, amines, andthiols, may also be used. For another example, vinyl alcohol-vinylacetate-silyl ether terpolymer can be used. An example vinylalcohol-vinyl acetate-silyl ether terpolymer is Exceval R-2015,available from Kuraray Chemical Company. In some embodiments,combinations of stabilizers are used.

In some embodiments, the wax emulsion comprises one or more of a base.For example, the wax emulsion may comprise an alkali metal hydroxide,such as potassium hydroxide or other suitable metallic hydroxide, suchas aluminum, barium, calcium, lithium, magnesium, sodium and/or zinchydroxide or calcium carbonate. These materials may also serve assaponifying agents. Non-metallic bases such as derivatives of ammonia aswell as amines (e.g., diethanolamine, triethanolamine, ormonoethanolamine) can also be used. Combinations of the above-mentionedmaterials are also possible. If included in the wax emulsion, one ormore of the base may be present in an amount of about 0% to about 35%.In other embodiments, the base may be present in an amount of about 0.1%to about 20% by weight of the wax emulsion. In further embodiments, thebase may be present in an amount of about 5 to about 15% by weight ofthe wax emulsion.

Another optional component of the emulsions described herein is arheology modifier or thickener which regulates the viscosity of theemulsion. In one embodiment, the rheology modifier increases theviscosity of the emulsion. In another embodiment, the thickener is acellulose ether such as a hydroxypropyl methyl cellulose. In oneexample, the thickener is one or more Methocel® products (K15M5) orpolyurethane resin such as Acrysol™ SCT-275 product. In a furtherembodiment, the rheology modifier is a hydrophobically modified ethyleneoxide-urethane block copolymer (HEUR) thickener. In another embodiment,the HEUR thickener has a molecular weight of about 10,000 to about50,000. In a further embodiment, the HEUR thickener contains nonionichydrophobic polymers. In still a further aspect, the polymer of the HEURthickener is end-capped with hydrophobic segments including, withoutlimitation, oleyl, stearyl, dodecylphenyl or nonylphenol. In anotherembodiment the polymer of the HEUR thickener contains at least twoterminal hydrophobic polyether or polyester groups such as polyesters ofmaleic acid and ethylene glycol and polyethers, such as polyethyleneglycol or polyethylene glycol derivatives. One of skill in the art wouldbe able to select a suitable amount of thickener for use in theemulsions described herein. In certain embodiments, the emulsionscomprise about 0.1 to about 4% by weight of a thickener. In otherembodiments, the emulsions comprise about 0.1 to about 1% by weight of athickener.

A further component of the emulsions may include an absorbent. In oneembodiment, the absorbent has particles of about 0.15 to about 0.55 mmand a high surface area. In a further embodiment, the absorbent isactivated carbon. In another embodiment, the high surface area chemicalis powdered activated carbon. In certain embodiments, the emulsionscontain about 0 to about 25% by weight of the absorbent. In otherembodiments, the emulsions contain about 0.1 to about 10% by weight ofthe absorbent. In further embodiments, the emulsions contain about 1 toabout 5% by weight of the absorbent.

Yet another component of the emulsions may include a defoamer. One ofskill in the art would be able to select a defoamer for the compositionsdescribed herein based on the PCM properties desired. In one embodiment,the defoamer contains one or more of Foamaster® VF—now MO2185. In afurther embodiment, the defoamer is the Foamaster® MO 2185 reagent whichcontains hydrotreated heavy napthenic distillates, a polyether polyol,solvent-dewaxed heavy paraffinic distillates, fatty acids, dioleatepolyethylene glycol, silica compound, and an oxidized polymer. Incertain embodiments, the emulsions contain about 0 to about 2% by weightof the defoamer. In other embodiments, the emulsions contain about 0 toabout 1% by weight of the defoamer. In further embodiments, theemulsions contain about 0 to about 0.5% by weight of the defoamer.

In some embodiments, an exemplary wax emulsion comprises: about 30% toabout 60% by weight of water; about 0.1% to about 5% by weight of alignosulfonic acid or a salt thereof; about 0% to about 1% by weight ofpotassium hydroxide; about 30% to about 50% by weight of wax selectedfrom the group consisting of paraffin wax, slack wax and combinationsthereof; and about 0.1% to about 10% montan wax, and about 0.1 to 5% byweight of ethylene-vinyl alcohol-vinyl acetate terpolymer.

The wax emulsion may further include other additives, including withoutlimitation additional emulsifiers and stabilizers typically used in waxemulsions, flame retardants, lignocellulosic preserving agents,fungicides, insecticides, biocides, waxes, sizing agents, fillers,binders, additional adhesives and/or catalysts. Such additives arepreferably present in minor amounts and are provided in amounts whichwill not materially affect the resulting composite board properties.Preferably no more than 30% by weight, more preferably no more than 10%,and most preferably no more than 5% by weight of such additives arepresent in the wax emulsion.

Shown in the below tables are example embodiments of a wax emulsion,although other quantities in weight % may be used.

TABLE 2 Raw Material Quantity in Weight Percent Water 58 Polyvinylalcohol 2.70 Dispersant (Optional) 1.50 Paraffin Wax 34.30 Montan Wax3.50 Biocide 0.02

TABLE 2.1 Raw Material Quantity in Weight % Water 58.80 Polyvinylalcohol 2.80 Diethanol Amine 0.04 Paraffin Wax 34.80 Montan Wax 3.50Biocide 0.10

The wax emulsion may be prepared using any acceptable techniques knownin the art or to be developed for formulating wax emulsions, forexample, the wax(es) are preferably heated to a molten state and blendedtogether (if blending is required). A hot aqueous solution is preparedwhich includes any additives such as emulsifiers, stabilizers, etc.,ethylene-vinyl alcohol-vinyl acetate terpolymer (if present), potassiumhydroxide (if present) and lignosulfonic acid or any salt thereof. Thewax is then metered together with the aqueous solution in appropriateproportions through a colloid mill or similar apparatus to form a waxemulsion, which may then be cooled to ambient conditions if desired.

In some embodiments, the wax emulsion may be incorporated with or coatedon various surfaces and substrates. For example, the wax emulsion may bemixed with gypsum to form a gypsum wallboard having improved moistureresistance properties.

Some or all steps of the above method may be performed in open vessels.However, the homogenizer may use pressure in its application.

Advantageously in some embodiments, the emulsion, once formed, is cooledquickly. By cooling the emulsion quickly, agglomeration and coalescenceof the wax particles may be avoided.

In some embodiments the wax mixture and the aqueous solution arecombined in a pre-mix tank before they are pumped into the colloid millor homogenizer. In other embodiments, the wax mixture and the aqueoussolution may be combined for the first time in the colloid mill orhomogenizer. When the wax mixture and the aqueous solution are combinedin the colloid mill or homogenizer without first being combined in apre-mix tank, the two mixtures may advantageously be combined underequivalent or nearly equivalent pressure or flow rate to ensuresufficient mixing.

In some embodiments, once melted, the wax emulsion is quickly combinedwith the aqueous solution. While not wishing to be bound by any theory,this expedited combination may beneficially prevent oxidation of the waxmixture.

Water-Resistant Products Comprising CPWB Microstructure Powders

Embodiments of the disclosed wax-based colloidal dispersions can be usedto form many different water-resistant products and as phase changematerial. For example, embodiments of powders made from wax emulsiondisclosed above can be used an additive to form a water-resistant jointcompound. The joint compound can be used to cover, smooth, or finishgaps in boards, such as joints between adjacent boards, screw holes, andnail holes. The joint compound can also be used for repairing surfacedefects on walls and applying texture to walls and ceilings amongstnumerous other applications. The joint compound can also be speciallyformulated to serve as a cover coat on cement and concrete surfaces. Thejoint compound can be particularly useful in locations where there ishigh humidity, such as bathrooms, to prevent molding or otherdeleterious effects.

Also, embodiments of powders formed from wax emulsion described abovecan be incorporated into building materials such as asphalt (e.g.,comprising a viscous liquid or semi-solid form of petroleum), concrete(e.g., comprising aggregate or filler, cement, water, various chemicaland/or mineral admixtures, etc.), stucco, cement (e.g., formed from orcomprising calcium carbonate, clay, gypsum, fly ash, ground granulatedblast furnace slag, lime and/or other alkalis, air entertainers,retarders, and/or coloring agents) or other binders. In someembodiments, powders formed from the wax emulsion can be incorporatedinto concrete cover coat formulations, such as those used for filling,smoothing, and/or finishing interior concrete surfaces, drywall tape,bead embedment, skim coating, and texturing drywall. Further,embodiments of the wax emulsion can be incorporated into concrete and/orcement mixtures as a water repellent additive. Therefore, embodiments ofthe powders formed from wax emulsion can be incorporated into pourableconcrete and/or cement that can be used, for example, for foundations inhome constructions. Additionally, embodiments of the powders formed fromwax emulsion can be used in cinder blocks as well as other similarconcrete or cement based products.

Embodiments of the powders formed from wax emulsion can also beincorporated into boards, such as cement boards (e.g., a relatively thinboard, comprising cement bonded particle boards and cement fiber (e.g.,comprising cement, fillers, cellulose, mica, etc.), which may be0.25-0.5 inch thick or which may be thicker or thinner), and/or cementboard formulations. Therefore, the wax emulsion can be used to provideadditional water resistance of the boards, and potentially prevent wateror water vapor from penetrating the boards.

Additionally, powders formed from embodiments of the wax emulsion can beincorporated into paint and/or paint formulations (e.g. a liquid,liquefiable, or mastic composition that, after application to asubstrate in a thin layer, converts to a solid film), such as paint thatmay be used to protect, color, or provide texture to a substrate. Thiscan be done to impart water repellency, or water resistance, to thepaint. The type of paint is not limiting, and embodiments of the waxemulsion can be incorporated into oil, water, acrylic, or latex basedpaints, including paints that may be pigmented to add color to thesubstrate on which the paint is applied. This water resistant paint canthen be used on exterior and interior surfaces of buildings, as well asother products such as vehicles (e.g. cars, boats, and planes), toys,furniture.

While the above detailed description has shown, described, and pointedout features as applied to various embodiments, it will be understoodthat various omissions, substitutions, and changes in the form anddetails of the devices or algorithms illustrated can be made withoutdeparting from the spirit of the disclosure. For example, certainpercentages and/or ratios of component ingredients have been describedwith respect to certain example embodiments; however, other percentagesand ratios may be used. Certain process have been described, howeverother embodiments may include fewer or additional states. As will berecognized, certain embodiments of the inventions described herein canbe embodied within a form that does not provide all of the advantages,features and benefits set forth herein, as some features can be used orpracticed separately from others.

EXPERIMENTAL Examples 1-7

Aqualite® 484 which is an emulsion from the Henry Company was spraydried to form particulate material from the emulsion. Aqualite® 484emulsion was added directly to a 300-gallon mixing tank with moderateagitation. The solids content of the emulsion was also calculated. Asolids result of 40.5% for the liquid was found. From the mixing tank,the emulsion was fed to the drying chamber of the spray drying equipmentthrough a two-fluid internal mix spray nozzle. The second fluid used wasair (at multiple pressures) to atomize the liquid into droplets. Fromthe drying chamber, powder was conveyed to a baghouse system. Powder wascollected directly from the baghouse and sifted through a 10-mesh screento remove any oversized powder agglomerates from the final product. Noinorganic flow agent was used during this trial. The product waspackaged in drums. The weight of each drum was dependent on how often adryer condition was changed. The powder samples were all tested formoisture content, particle size, and bulk density. Drying was performedat temperature between 115° F. and 140° F. (inlet) and 175° F. and 200°F. (outlet) and an atomization pressure of 120-130 psi. The meltingpoint of the product is 140° F. The moisture content of the finishedproduct was 1.26%. Particle size was measured for each test. The resultsare tabulated in Table 3. The D(10) particle size indicates the biggestaverage particle size that covers 10% of the material. D(50) indicatesthe average particle size below which 50% of the particles are found.

TABLE 3 Final Moisture Particle Content Size Particle Size Particle SizeNo. (%)* D(10) D(50) D(90) LBD/PBD 1. 1.26 37.03 93.28 307.60 0.28/0.312. 0.78 39.58 109.90 367.50 0.29/0.32 3. 0.69 46.01 150.80 533.700.30/0.35 4. 0.68 116.40 333.70 884.40 0.30/0.33 5. 2.37 80.00 264.40660.90 0.31/0.35 6. 0.38 59.32 172.60 441.10 0.26/0.29 7. 0.45 60.91168.00 497.10 0.31/0.34 *Initial moisture content was 40.5% solids

FIG. 3 (AA AQ484-P Neat 100814-AA) is a DSC at a heating rate of 5°C./min of the neat powder wax emulsion (the one used in Examples 1-7above). The paraffin used has a melting point of around 56° C. Thelatent heat of fusion is around 130 J/g. FIG. 4 shows a DSC plot(AA-082514-1) at a heating rate of 5° C./min of the same powder waxemulsion that was mixed with calcium carbonate (a ratio of 28% powderwax emulsion to 72% calcium carbonate). A cycle of heating and coolingwas performed and repeated ten times. It was observed that other thanthe first cycle (removal of entrained air, etc.), all the other cycleswere perfectly congruent, with minimal to no hysteresis. FIG. 5 shows aDSC of a coating formulation (WRP-061014-4AA) containing 30% wet dosageof the wax emulsion. This confirms that whether dry or wet, the waxemulsion acts as a phase change material. The repeat cycles showing thesame thermal characteristics essentially shows that the materials couldbe used as phase change materials with a heat transition happening inthe neighborhood of the melting point of the wax.

This invention also relates to those paraffins or waxes that are liquidat room temperature but have sub-zero melting points. While the emulsionwould have colloidally-protected wax-based microstructures that have asolid shell and a liquid core, these materials could be used at sub-zerotemperatures to maintain temperatures through a heating and a coolingcycle. For example, the C₁₂ hydrocarbon dodecane melts at −10° C. andthe C₁₁ melts at −26° C. However, both are liquids at room temperature.One could use these materials to be emulsified with the polymericmaterials mentioned previously to form the colloidally-protected waxalkane hydrocarbon structures, which can then be dried at lowertemperatures or freeze dried to remove the water content and thenpowderized to now act as PCMs at sub-zero temperatures. These materialswould have applications in the medical field or even in the foodapplications where the temperatures need to be maintained at sub-zerobut without major fluctuations. Clearly, these materials cannot beclassified as waxes, but lower hydrocarbons. But these lowerhydrocarbons can also be emulsified and then rendered into powders tosub-zero usage as PCMs. Note that once the hydrocarbon alkane material,albeit in a liquid form, is trapped in the colloidally-protected form,when the water is removed, it will remain intact and not escape into thegaseous phase by evaporation (these are lighter fractions than waxes),colloidally protected by the secondary forces.

Table 4 relates to the coating prepared for K-Factor testing. A coatingwas prepared with the AquaDri® emulsion where Rubitherm® 28 paraffin(melting point of 28° C.) was used. In a second example Rubitherm® 21(melting point of 21° C.) was used.

TABLE 4 Coating for K-factor testing Wt. Solids wt. AquaDri (46%, highPVOH, Rubitherm 28) = 150 69 Attagel 30 = 2.85 2.85 Calcium carbonateImerys MW100) = 20 20 Acronal NX4787 = 10 5 Total = 182.85 96.85 %Solids = 53.0% AquaDri 46%, Rubitherm 21 = 150 69 Attagel 30 = 3.35 3.35Calcium carbonate (Imerys, MW 100) = 20 20 Acronal NX4787 = 10 5 Total =183.35 97.35 % Solids = 53.1%

Example 8

The components of the PCM Wax Emulsion identified in Table 5 werecombined.

TABLE 5 PCM Wax Emulsion Component Amount (g) Water 421.26 Selvol 310(polyvinyl alcohol, Seiki-Sui) 36.5 PCM Paraffin 303 Stearic Acid 18.7Monoethanol amine 1.8 Acticide CBM2 (Thor Company) 0.5 Total Wt. 781.76Solids 360 Solids (%) 46.0% PCM Paraffin (%) 38.8% PCM Paraffin insolids (%) 84.2%

The PCM Coating Formula was then prepared by combining the PCM waxemulsion above with the components of Table 6.

TABLE 6 PCM Coating Amount Solids Actives % in Component (g) (%) Weight(g) Solids Water 19.4 0 0 0.0 Darvan 811 (RT Vanderbilt) 3.5 43 1.5 1.8Foamaster VF (Cognis) 0.2 0.0 Mg(OH)₂ (Garrison Materials) 18.2 100 18.221.7 Methocel K15MS 1 100 1.0 (Dow Chemical) Activated Carbon (5583,Asbury 8 100 8.0 9.5 Carbon) Acronal NX4787 (BASF) 18.3 50.00 9.2 10.9Acticide MKW2 0.75 (Thor Company) PCM Emulsion (90050A) 100 46 46.0 54.9Total 169.35 83.9 98.8 Coating formula solids (%) 49.5 Paraffin incoating (%) 22.9 Paraffin in dry coating (%) 46.2

From the mixing tank, the emulsion was fed to the drying chamber of thespray drying equipment through a two-fluid internal mix spray nozzle.The second fluid used was air (at multiple pressures) to atomize theliquid into droplets. From the drying chamber, powder was conveyed to abaghouse system. Powder was collected directly from the baghouse andsifted through a 10-mesh screen to remove any oversized powderagglomerates from the final product. No inorganic flow agent was usedduring this trial. The product was packaged in drums. The weight of eachdrum was dependent on how often a dryer condition was changed. Thepowder samples were all tested for moisture content, particle size, andbulk density. Drying was performed at temperature between 115° F. and140° F. (inlet) and 175° F. and 200° F. (outlet) and an atomizationpressure of 120-130 psi.

As shown in Table 7 below, a coating formulation was prepared using awax emulsion comprising the Saraphaez 20 paraffin with a melting pointof about 30° C. The ratio of paraffin to PVOH in this example was about8:1. In one embodiment of the present invention, the ratio of theparaffin to PVOH (or any other polymer listed herein for preparing thewax emulsion) can be from about 4:1 to about 20:1. In other words, theratio can be 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1,15:1, 16:1, 17:1, 18:1, 19:1, and 20:1. The ratio can be within a rangedefined by any two of these numbers listed here.

As shown in Table, 8, the ratio is about 13. A lower ratio means ahigher concentration of PVOH. This allows for a more robust film to beformed around the paraffin. The film formed around the paraffin isadhered in part due to the emulsifying agents such as montan or otherwaxes (acids and/or esters) that “bridge” the paraffin to the PVOH.

In both Table 7 and 8, Rubitherm® RT paraffin (Rubitherm, Germany) wasused to prepare the wax emulsion. Rubitherm® is a well-known PCMparaffin material with the waxes ranging from −10 to 90° C. in meltingpoint. This invention shows a successful generation of Rubitherm®paraffin based colloidally-protected microstructures that can be used asPCMs in a variety of applications.

Coating formulations were prepared from the wax emulsions as describedin Table 7 and 8 below. In Table 7, example, CaCO₃ was added to controlthe leaking paraffin from the PCM wax-based microstructure into thecoating formulation. In Table 8, activated carbon was used to controlthe leaking. Even when the PVOH used in Table 8 was about half that ofwhat was used in Table 5, only about 0.5 g of activated carbon, or about2.5% by weight of the emulsion was required to control the bleeding.About 10% of CaCO₃ was used with a higher concentration of PVOH, but itdid not provide the same performance as activated carbon.

Apart from the CaCO₃, all the materials in Table 7 were added in theorder listed and mixed under high shear using a milkshake mixer. TheCaCO₃ was then added followed by further mixing. The resulting producthad good leveling and rheological properties. It made for a goodcoating. The coating was then applied onto one side of carefully cut out12″×12″ wallboard using a Gardner blade at different coating thicknesssettings. The settings used were 0.25, 0.5, and 1.0. The above settingsdid not correspond to coating mil thickness. For instance, a setting of1.0 gave a mil thickness of 96. The viscosity of this coating, measuredusing an RV Spindle #3 at 1.5 rpm, was 55,000 cps. The quantity of CaCO₃added to this coating formula was less than what was required to preventparaffin leaking based on an earlier smaller scale work. That said, itwas decided to explore the effect of a lower level of CaCO₃ when scalingup. In testing for leakage, a quantity of the coating was applied unto aweighed metal tray. This coating was then allowed to dry overnight. Whendried, the tray and the dried coating were weighed before being placedin a 50° C. oven (standing in a vertical position) for 30 minutes. Whenremoved from the oven, any leaking paraffin was wiped away using a softpaper towel. The tray was then weighed and the amount of paraffin lostcomputed.

TABLE 7 PCM-Wax emulsion using Alpha Wax's Saraphaez 20 PCM paraffin (MP85° F., about 30° C.) Wax emulsion (81137A) PCM formula: 81137Aformula - Water = 421.26 g Selvol 310 (polyvinyl alcohol) = 36.5 gSaraphaez 20 paraffin = 303 g Stearic Acid = 18.7 g Monoethanol amine =1.8 g Total Wt. 781.26 g Acticide CBM2 (preservative) 2 drops FoamsterVF (Defoamer) 2 drops Emulsion viscosity, measured at 86° F. = 3320 cps% Selvol 310 of solids = 10.1% % Solids = 46.1% % Saraphaez 20 in Solids= 84.2% Coating formulation: Wt. of 81137A = 500.0 g Wt. of Darvan 811 =3.0 g Wt. of Acrysol SCT 275 = 9.0 g Wt. of Foamaster VF = 0.5 g Wt. ofCaCO₃ (MW 100, Imerys) = 50.0 g Total 562.5 g Coatings % Solids = 50.66%Wt. of Coatings Solids = 284.97 g Wt. of solids from 81137A = 230.4 gWt. of Saraphaez 20 coating solids = 193.9 g % Saraphaez 20 in CoatingsSolids = 68.0% 0.25 0.5 1.0 Wt. of metal tray = 30.0527 g Wt. of tray +81137A-Coating = 34.4155 g The coating on the metal tray above was driedovernight, Theoretical wt. of dried coating = 2.2103 g Actual weights:Wt. of tray + dried 81137A-Coating = 32.3734 g Wt. of dried coating =2.3207 g Estimated amount of Saraphaez 20 = 1.5792 g Estimated amount ofother solids = 0.7415 g After drying in oven at 50° C. for 30 mins, Wt.of tray + oven dried 81137A-Coating = 32.2410 g Wt. of dried coating =2.1883 g Amt. of other solids = 0.7415 g Amt. of Saraphaez 20 remaining= 1.4468 g % Saraphaez 20 retained = 91.6%

TABLE 8 Leak free PCM coating using Rubitherm ® RT21 PCM paraffin (MP21° C.) wax emulsion Wax emulsion (81112B) PCM formula: 81112B formula -Water = 421.26 g Selvol 310 (polyvinyl alcohol) = 19.6 g Rubitherm RT21= 249.2 g Stearic Acid = 7.7 g Monoethanol amine = 0.5 g Total Wt.698.26 g Acticide CBM2 (preservative) 2 drops Foamster VF (Defoamer) 2drops Emulsion viscosity, measured at 86° F. = 192 cps % Selvol 310 ofsolids =  7.1% % Solids = 39.7% % Rubitherm RT21 in Solids = 90.0%Coating formulation: Wt. of 81112B = 19.0 g Wt. of Acronal NX4787 latex= 2.0 g Wt. of Acrysol SCT 275 = 1.0 g Activated Carbon (Asbury Carbon,#5597) = 0.5 g Total 22.5 g Coatings % Solids = 45.39%  Wt. of CoatingsSolids = 10.21 g Wt. of solids from 81112B = 7.5 g Wt. of Rubitherm RT21coating solids = 6.8 g % Rubitherm RT21 in Coatings Solids = 66.4%

In one embodiment, the coating formulation prepared according to thepresent invention is applied and sandwiched between two wallboards toprovide a coating layer that acts as a PCM material. For preparingsoundproof boards, viscoelastic layer is applied and sandwiched betweentwo wallboards. This invention envisions applying the soundproofingviscoelastic layer, for example on one side of one wallboard andapplying the coating formulation comprising the PCMs on the otherwallboard, bringing together the two wallboards to sandwich the PCMcoating layer as well as the viscoelastic layer. In one embodiment, thisinvention envisions mixing the coating layer with the viscoelasticlayer.

In one embodiment, for example in roofing applications, where fiberglasspaper and asphalt binder is used, instead, a coating formulationdescribed above can be used which will provide adhesion,water-repellency, and PCM properties. This invention envisions forexample using the formulations and PCMs described herein for interiorwalls, ceiling/attic, exterior sheathing walls, roofing, and floor panelpurposes. For these applications, the preferred temperature range of PCMapplication is from 70° F. to 150° F. and the PCMs and formulations ofthe present invention can be used for it.

The invention claimed is:
 1. A phase change material (PCM) comprisingcolloidally-protected wax-based (CPWB) microstructures and an absorbentmaterial.
 2. The PCM as recited in claim 1, wherein: (I) said CPWBmicrostructure comprises: (A) a wax core, and (B) a polymeric shell;wherein said wax core comprises a paraffin component and a non-paraffincomponent; wherein said paraffin component comprises at least one linearalkane wax defined by the general formula CnH2n+2, where n ranges from13-80; wherein said non-paraffin component comprises at least one waxselected from the group consisting of animal-based wax, plant-based wax,mineral wax, synthetic wax, a wax containing organic acids and/oresters, anhydrides, an emulsifier containing a mixture of organic acidsand/or esters, and combinations thereof; and wherein said polymericshell comprises at least one polymer selected from the group consistingof polyvinyl alcohol and copolymers, cellulose ethers, polyethyleneoxide, polyethyleneimines, polyvinylpyrrolidone, and copolymers,polyethylene glycol, polyacrylamides and poly (N-isopropylamides),pullulan, sodium alginate, gelatin, starches, and combinations thereof,and (II) said absorbent material comprises at least one of activatedcarbon, graphite, bentonite, deposited carbon, silica gel, activatedalumina, zeolites, molecular sieves, alkali metal alumino-silicate,silica-magnesia gel, silica-alumina gel, activated alumina, calciumoxide, calcium carbonate, clay, diatomaceous earth, cyclodextrin, or acombination thereof.
 3. The PCM as recited in claim 2, wherein saidabsorbent material is in the range of from about 0.1% to about 25% byweight of said PCM.
 4. The PCM as recited in claim 3, wherein saidabsorbent material is activated carbon and said activated carbon ispowdered carbon, granular activated carbon, or a mixture thereof.
 5. ThePCM as recited in claim 1, wherein said PCM's temperature operatingrange is defined by the melting point of said paraffin componentcomprising at least one linear alkane wax defined by the general formulaC_(n)H_(2n+2), where n ranges from 13-80, and wherein said temperatureoperating range is characterized the corresponding pressure of thesystem in which said PCM is used.
 6. The PCM as recited in claim 5,wherein said PCM's temperature operating range is from −6° C. to 140°.7. A process for preparing the PCM of claim 1 comprising contacting CPWBmicrostructures with an absorbent material to from said PCM.
 8. Theprocess as recited in claim 7, wherein: (I) said CPWB microstructurecomprises: (A) a wax core, and (B) a polymeric shell; wherein said waxcore comprises a paraffin component and a non-paraffin component;wherein said paraffin component comprises at least one linear alkane waxdefined by the general formula CnH2n+2, where n ranges from 13-80;wherein said non-paraffin component comprises at least one wax selectedfrom the group consisting of animal-based wax, plant-based wax, mineralwax, synthetic wax, a wax containing organic acids and/or esters,anhydrides, an emulsifier containing a mixture of organic acids and/oresters, and combinations thereof; and wherein said polymeric shellcomprises at least one polymer selected from the group consisting ofpolyvinyl alcohol and copolymers, cellulose ethers, polyethylene oxide,polyethyleneimines, polyvinylpyrrolidone, and copolymers, polyethyleneglycol, polyacrylamides and poly (N-isopropylamides), pullulan, sodiumalginate, gelatin, starches, and combinations thereof, and (II) saidabsorbent material comprises at least one of activated carbon, graphite,bentonite, deposited carbon, silica gel, activated alumina, zeolites,molecular sieves, alkali metal alumino-silicate, silica-magnesia gel,silica-alumina gel, activated alumina, calcium oxide, calcium carbonate,clay, diatomaceous earth, cyclodextrin, or a combination thereof.
 9. Theprocess as recited in claim 7, wherein said absorbent material is in therange of from about 0.1% to about 25% by weight of said PCM.
 10. Theprocess as recited in claim 8, wherein said absorbent material isactivated carbon and said activated carbon is powdered carbon, granularactivated carbon, or a mixture thereof.
 11. The process as recited inclaim 8, wherein said PCM's temperature operating range is defined bythe melting point of said paraffin component comprising at least onelinear alkane wax defined by the general formula C_(n)H_(2n+2), where nranges from 13-80, and wherein said temperature operating range ischaracterized the corresponding pressure of the system in which said PCMis used.
 12. The process as recited in claim 11, wherein said PCM'stemperature operating range is from −6° C. to 140°.
 13. A process forpreparing a powder form of PCM as recited in claim 1, the processcomprising the steps of: (I) providing CPWB microstructures in aqueouswax emulsion form; (II) subjecting said PCM to at least onepowder-making process; and (III) optionally subjecting the resultingpowder from step (II) to a size reduction process; wherein said emulsionis optionally subjected to additional drying before, during, or aftersaid at least one powder-making process; wherein said at least onepowder-making process is selected from the group consisting of freezedrying; lyophilization, vacuum drying; air drying; spray drying;atomization; evaporation; tray drying; flash drying; drum drying;fluid-bed drying; oven drying; belt drying; microwave drying; solardrying; linear combinations thereof; and parallel combinations thereof;and (IV) incorporating an absorbent material with said powder of step(II).
 14. The powder prepared by the process of claim
 13. 15. The powderas recited in claim 14, wherein said powder form of PCM comprisesparticles in the average particle size range of from about 1 to about1000 micron.
 16. The powder as recited in claim 14, wherein said powderform of PCM comprises particles such that about 10%, 50% and/or 90% ofthe particles by weight are less than the average particle size withinthe range of from 1 to 1000 micron.
 17. The powder as recited in claim14, wherein said powder comprises dried 1-5 mm chips.
 18. A process forimproving a matrix structure's ability to dampen temperaturefluctuations, comprising: (I) contacting CPWB microstructures with afirst absorbent material to from a PCM; (II) incorporating said PCM fromstep (I) into said matrix structure, and (III) optionally incorporatinga second absorbent material to said matrix structure.
 19. The process asrecited in claim 18, wherein: (I) said CPWB microstructure comprises:(A) a wax core, and (B) a polymeric shell; wherein said wax corecomprises a paraffin component and a non-paraffin component; whereinsaid paraffin component comprises at least one linear alkane wax definedby the general formula CnH2n+2, where n ranges from 13-80; wherein saidnon-paraffin component comprises at least one wax selected from thegroup consisting of animal-based wax, plant-based wax, mineral wax,synthetic wax, a wax containing organic acids and/or esters, anhydrides,an emulsifier containing a mixture of organic acids and/or esters, andcombinations thereof and wherein said polymeric shell comprises at leastone polymer selected from the group consisting of polyvinyl alcohol andcopolymers, cellulose ethers, polyethylene oxide, polyethyleneimines,polyvinylpyrrolidone, and copolymers, polyethylene glycol,polyacrylamides and poly (N-isopropylamides), pullulan, sodium alginate,gelatin, starches, and combinations thereof, and (II) said firstabsorbent material and said second absorbent material comprise at leastone of activated carbon, graphite, bentonite, deposited carbon, silicagel, activated alumina, zeolites, molecular sieves, alkali metalalumino-silicate, silica-magnesia gel, silica-alumina gel, activatedalumina, calcium oxide, calcium carbonate, clay, diatomaceous earth,cyclodextrin, or a combination thereof.
 20. The process as recited inclaim 19, wherein said first absorbent material is in the range of fromabout 0.1% to about 25% by weight of said PCM.
 21. The process asrecited in claim 20, wherein said first absorbent material and/or saidsecond absorbent material is activated carbon and said activated carbonis powdered carbon, granular activated carbon, or a mixture thereof. 22.The process as recited in claim 18, wherein said PCM's temperatureoperating range is defined by the melting point of said paraffincomponent comprising at least one linear alkane wax defined by thegeneral formula C_(n)H_(2n+2), where n ranges from 13-80, and whereinsaid temperature operating range is characterized the correspondingpressure of the system in which said PCM is used.
 23. The process asrecited in claim 22, wherein said PCM's temperature operating range isfrom −6° C. to 140°.
 24. A matrix structure comprising said PCM asrecited in claim
 1. 25. The matrix structure as recited in claim 24,wherein said PCM is in an aqueous emulsion form or a powder form. 26.The matrix structure as recited in claim 24, wherein the dry-solidsweight percent of said PCM in said aqueous emulsion form, by weight ofsaid matrix structure is in the range of from 10% to 50%; and whereinthe solids weight content of the PCM in said dry powder form is in therange of from 1% to 50% by weight of said matrix structure, and saidabsorbent is in the range of from about 0.1% to about 25% of said PCM.27. The matrix structure as recited in claim 24, wherein said matrixstructure is a construction wall.
 28. The matrix structure as recited inclaim 27, wherein said PCM is in fine particle form and is coated on apaper or a plastic sheet.